Motor vehicles that are driven by means of an internal combustion engine contribute to reduced air quality, particularly in densely populated areas such as for example inner cities. The effects of vehicle emissions have been widely reported. In some areas, air quality varies at certain times.
Various measures are employed to reduce vehicle emissions. On the one hand, methods for reducing the vehicle emissions are continually being developed and implemented to meet the respectively applicable exhaust standards. On the other hand, measures are also taken to limit the vehicle density in areas that are particularly affected by air quality issues. Thus for example, on reaching certain low air quality values, the license plates for certain vehicles (for example those with odd numbered or with even-numbered license plates) can be restricted. In other cases, access to certain urban areas for vehicles that do not meet the current exhaust standards is prohibited.